Contact fingers and contact devices in accordance with above are previously known in the art. More precisely, contact devices are previously known in the art in particular for high current strengths, where the contact devices are intended to be connected to the end of a cable for interconnection of one or more cables to one another. The contact devices comprise an outer housing, typically manufactured from plastic, contact fingers for the actual electrical connection, and a metal spring associated with each contact finger in order to generate such a force on each respective contact finger that they, in the connected state, are biased towards one another for maintaining good contact, whereby sparking or undesirable overheating because of a defective contact between the contact fingers is intended to be avoided.
Those parts that are intended to be in direct physical contact with one another moreover display a standardised design so that contact devices from different manufacturers may marry together with one another.
The springing which was mentioned above has thus hitherto been used to realise a good contact between the contact fingers. Certainly, this functions satisfactorily, but at high current strengths it has proved that the springing is not always sufficient to entirely prevent sparking or undesirable overheating. The term “higher current strengths” is taken in this context to signify current strengths that are higher than those for which the contact device in question is classified. At the same time, the stiffness of the metal spring cannot be further increased for a classification for increased current strength while retaining the same physical dimensions, since interconnection and disconnection of the contact devices which, to some degree, take place against the action of the spring, must still be possible. The reason for the defective contact at higher current strengths is thus assumed principally to be insufficient contact pressure or otherwise a far too limited contact surface area.
A further problem is that the contact fingers, when they are connected each to a cable end, can be affected thereby when the contact devices are moved, in particular if the cables are heavy and stiff. In such instance, the contact fingers may slip in relation to one another and in the even of unevenness, play may readily occur between them. Nor is the position of the contact fingers in relation to one another or to the contact housing a matter of absolute certainty.
Another problem may be random and unpredictable unevenness in the material, which may possibly have occurred during manufacture. It may be the contact fingers themselves that are uneven, so that contact only takes place at some individual point instead of along a line, which is intended. Possibly, the contact fingers may flip around such a contact point, at least in the even of insufficient contact pressure, which will give rise to problems involving sparking and undesirable overheating as described above.
The contact springs may also partly contribute to these undesirable properties, in that they do not exactly correspond to the established norms and requirement specifications and, as a result, deliver a spring force which is not uniform throughout the entire width of the contact finger.
While these problems may in principle be circumvented by replacing an existing contact device with a higher classification as regards current strength, this is not often desirable, on the one hand for reasons of space and on the other hand for reasons of cost.
Problem Structure
There is thus one object of the present invention to realise a contact finger and contact device, respectively, where sufficiently good contact is obtained in order to make for use at higher current strengths than has hitherto been possible, at the same time as the outer dimensions of the contact device are maintained unchanged.
Solution
The object forming the basis of the present invention will be attained concerning the contact finger if this is characterised in that the contact member is provided with a series of grooves for improved contact efficiency.
Further advantages will be attained if the contact finger is moreover given one or more of the characterising features as set forth in appended subclaims 2 to 8.
Concerning the contact device, the object of the present invention will be attained if this includes a contact finger in accordance with the foregoing.